Electrical sound reproducing apparatus



Sept. 19, 1933. 'r. M. EDISON ELECTRICAL SOUND REPRODUCING APPARATUS Filed July 18 1950 l J L35 0 Z28 R E m W m NV mm m A BY M? aw/w 25 Patented Sept. 19 1933 ELECTRICAL PATENT OFFICE SOUND REPRODUCING APPARATUS Theodore M. Edison, East Orange, N. J., as-

signor to Thomas A. Edison, Incorporated, West Orange, N. J., a corporation of New Jersey Application July 18, 1930. Serial No. 468,917 14 Claims. (01; ire-100.41)

This invention relates to electrical sound reproducing apparatus and, more particularly, to an electrical phonograph pick-up arranged to operate from a mechanical record to produce voltage or current variations corresponding to the sounds to be reproduced.

It is an object of this invention to provide an electrical pick-up device, arranged to be selectively operable by one of a plurality of styli, and

cooperating with either lateral cut or hill and dale records, and in which no change in the angle or position of the pick-up is required when the type of record to be played is changed.

A still further object is to provide a pick-up in 1,5 which the armature pivot is located at substantially the lowest point of the pick-up and in which the armature is supported at the top as well as at the bottom.

Still a further object of my invention is to produce'a pick-up capable of delivering an output of high quality, which shall be compact and reliable, Still other objects and advantages of my inventionwill be apparent from the specification. The features of novelty which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its fundamental principles anda's to its particular embodiments will be best understood by reference to the specification and accompanying drawing, in which:-

Figure 1 shows a front elevation, parts being broken away and in section to more clearly show the construction;

Figure 2 shows a section along broken line 22 of Figure 1;

Figure 3 is a sectional view, partly broken away and on a reduced scale, on line 3--3 of Figure 1;

Figure 4 is a View also on a reduced scale, taken from the bottom of the pick-up with the bottom coverremoved, parts being broken away;

Figure 5 is a fragmentary view in cross-section of a part of the main body portion of the pickup with the pole pieces positioned thereon along the line 5 5 of Figure 1;

Figure 6 is a bottom plan view on a reduced scale, of the main body portion of the pick-up; and

Figure '7 is a detail sectional view, partly in elevation, of the armature mounting. n

' In the usual tone arm, as it is known, rotation of the entire tone arm is permitted in a horizontal plane, while a part of the arm is permitted to swingin a vertical plane. vIn such an arrangenon-magnetic material, preferably formed inment, there is more or less lost motion or play in the tone arm joints. This lost motion is objectionable, because it produces distortion of various kinds and undesired noises, which are delivered by the loud speaker;

An improved form of tone arm, substantially the whole of which is movable as a unit both vertically and horizontallyis shown in the copending application of Theodore M. Edison and Karl G. Berggren, entitled Electrical sound reproducing systems, Serial No. 468,918, filed July 18, 1930. The pick-up herein disclosed and claimed is particularly adapted for use with the tone arm therein shown, but it will be understood that its use is not limited thereto.

Referring now more particularly to thedrawing I have shown a pick-up having a main frame or body portion 1 composed preferably of nonmagnetic material, on which are mounted all of the operative elements of the pick-up. The neck 2 is preferably provided with a passage 3 extending at an angle to a point below the center of the upright portion 5 of the body portion and the assembled unit. The passage 3 is preferably counterbored to receive a spring 6, abutting at one end the shoulder 8 and at the other end, the shoulder 9 of the counterbore, thus retaining the spring in position. v

The pick-up is mounted on the tone arm as shown in the application. above referred to, by sliding the neck 2 .over the sleeve portion of the tone arm, a shoulder on the tone arm abutting the outer end of the spring 6, and compressing it. The tone arm is interlocked with the neck by means of the pin 11 projecting into the bore 3 through a bayonet slot or other provision on the tone arm. By thus maintaining the spring under tension exerted against each part, rigidity is more easilyv attained in this connection. I

The portion 5 of the main body is preferably arranged to be at an angle of approximately 10 degrees with the vertical in playing position, as will be hereafter more particularly set forth, and neck 2 is therefore formed on a center line which intersects body 5 at such an angle that when the pick-up is mounted on the tone arm in playing position, the proper angular relation exists.

- Body portion 1, at the lower end thereof, is provided with a forwardly extending ledge 13,0f

tegrally therewith and provided with a central opening through which the armature passes. A

slot 80 extending from the opening to the other edge of ledge 13 is provided to prevent the ledge acting as a short circuited turn in operation of the be. understood.

pick-up and also acting to prevent eddy currents being set up in said ledge. Secured to the ledge by screws 15 are the pole pieces 17 and 18, each of the same offset shape. Between "the offset pole pieces and the ledge 13 is positioned the coil 22, preferably having a bobbin of rectangular outside and inside configuration.

The ledge 13 in its central part is preferably provided with a semi-circular groove 25, affording a suitable bearing upon the main body portion for the cylindrical extensions 2'? and 28 of the armature element 23. The armature itself and its extensions 2'7 and 28 are of magnetic material but extensions 27 and 28 are preferably provided with sleeves 27a and 28a of non-magnetic material, and the armature is flattened and widened at its upper end. The extensions 27 and 28 are resiliently held in place in groove by the clamps 19 and 20 which. may be and preferably are of mag netic material and which are provided with interfittingsurfaces 30 and 31. Proper lateral alignment by. adjustment is afforded by the slots 32 through which are inserted the screws 33 for securing the clamps 19 and 20 in position. One of these clamps may be cut away as at 35a to provide a clearance space for the laterally extending stylus arm 35.

Inorder to prevent undue friction or chattering and to permit the necessary movement between the armature and its bearing, rubber sleeves 37 and 38 are provided over the armature extensions 27 and 28 to separate them from metallic contact with their supports and to provide a cer tain amount of damping. Small strips of rubber may be used in place of the sleeves 37 and 38 if desired.

The upper ends of the oifset pole pieces are tapered and provided with slots '40 and 41, as shown in Figure 3. Slotted washers 42 and 43 arranged above eccentric washers 44 and 45 are held in place on said pole pieces by screws 4'7 and .48. The slotted washers preferably have downward extensions and 51 extending into the slotted ends of the'pole pieces, between which are positioned the rubber blocks or buffers 53 with the upper end of the armature interleaved therebetween. This arrangement holds the end of the armature away from the pole pieces and modifies its vibrational movement in the desired manner. Optimum adjustment of these dampers 53 for desired results may be obtained by loosening screws 47 and 48. The eccentric washers 44 and 45 may be arranged to obtain this adjustment by rotating them with some pointed instrument inserted in one of the notches in their periphery. The slotted washers 42 and 43 will be pressed into contact with the contour of theperiphery of eccentric washers 44 and 45 by the pressure exerted by the resilient material 53, against downward extensions 50 and 51 as will When the screws 47 and 48 are again tightened the parts will be permanently secured against movement. Thus by proper adjustment of the pressure on blocks 53 as described, the armature may be positioned in the gap and its damping controlled as desired.

The pole pieces are energized by a permanent magnet or other device 55 in position suitably secured on body portion 1, as by-screw 56 and plate 57. The magnet is preferably properly faced at its ends, as. at 58 and 59, so as to contact with the oifset pole pieces 17 and 18.

The stylus arm or holder 35 is arranged to carry a permanent stylus preferably in the form of a jewel to cooperate with the hill and dale type record, said holder extending substantially at right angles to the axis of the vibratory armature and slightly downward to permit proper clearance for the other parts. It will be noted, however, by reference to Figure 4 that arm 35 is given a slight rake or inclination in the direction of record movement, and is also set in with the same angle as the pick-up, but displaced in the opposite direction. That is to say, the center line of the pick-up, is displaced +l0 from vertical in playing position, and the arm 35 is displaced -10 from the center line of the pickup so that in playing position the jewel is truly normal to the record at all times. The central part of the vibratory member is drilled and thereafter broached at an angle of about 15 with the center line of the pick-up so that the stylus 61, or needle, inserted therein will be at least 25 degrees from the perpendicular with respect to the record with which it cooperates when in use. The needle is held in place by clamping means 62 passing r u h e ex ensio 2 hich ma be in the form of a thumb screw, asshown, or in any other desired form. V

A cover 65 provided with an opening to, accommodate the stylus holders may be secured to the lower side of the ledgel3 by means of screws 66 d s n n o, he A shield Q soft material such as sheet rubber provided with an opening may be tightly fitted about the lower end of the stylus elements so as to prevent the entrance of foreign material into the interior of the mechanism. The shield is preferably sufliciently flexible so as not to interfere the movement bf the vibratory member and when clamped between the clamps 19 and 20 and the lower cover will effectively keep out chips, particularly steel and iron chips which would otherwise tend to work into the air gap. 7

An upper cover 69 suitably held in placeasby screws 70 prevents the entrance of such materials from above and serves to give the unit a substantially smooth and sightly contour. A contact block '72 secured by screws to the main body may be used to fasten the terminals 7-3 and 74 of coil 22 from whichflexible connections '76 may be extended through neck 2 to suitableamplifying apparatus.

From this. construction it is apparent th-afiany of the working parts may readily be removed for repair or replacement without disturbing others of said parts, that all of the parts are secured directly to the main body portion where they receive the most secure support and that the arrangement of styli is such as to render each most eflicient in operation without detriment to the other. The permanent stylus may be used by simply removing the replaceable one and vibration in an undesired manner of the vibrating element is reduced to a minimum on account of the suspension of the element. It will be understood that by positioning the unit as a whole with the neck portion. below the center, that vibration of the tone arm and adjacent parts is minimized.

It is thus seen that there is provided a device in which the several objects of this invention are achieved and which is well adapted tomeet the conditions of practical use, and that various, possible embodiments might be made of the above invention. It is tobe understood that allmatter herein set forthor shown in the accompanying drawing is to be interpreted as illustrative, Q nly andnot in a limiting sense.

I claim:

n n el ct ca i kp. de ic a. ert ca vibratory member having horizontal extensions adjacent its lower end and an upwardly extending end vibratable in amagnetic field, means for supporting said member for pivotal movement including resilient material surrounding said extensions and a permanent stylus and a holder for a replaceable stylus secured to said member at its lower end. 1

2. In an electrical pick-up device, a vertical vibratory member having horizontal bearing extensions adjacent its lower end and an upwardly extending end vibratable in a magnetic field, means for supporting said member for restrained pivotal movement, an extension secured to said member extending at an angle thereto, and a permanent stylus mounted on said extension.

3. In an electrical pick-up device, a vertical vibratory member having horizontal extensions adjacent its lower end and an upwardly extending end vibratable in a magnetic field, means for resiliently supporting said member for pivotal movement, a permanent stylus and a holder for a replaceable stylus secured to said member, said permanent stylus extending laterally at a substantial angle to said extensions.

4. In a magnetic device, a magnet havingpole faces, pole pieces contacting with said magnet, a rigid non-magnetic member and clamping means adjacent said pole pieces, a vibratory member positioned between said pole pieces and pivotally supported between said non-magnetic member and said clamping means, and damping means controlling the position of said vibratory member.

5. In an electrical pick-up the combination of a vibratile armature, a coil associated therewith, a magnetic system for producing flux in said armature, a holder for a replaceable stylus formed'in said armature and a permanent stylus secured thereto, said permanent stylus being in the form of an arm extending downwardly and rearwardly therefrom.

6. In an electrical pick-up the combination of a vibratile armature, a coil associated therewith,

a magnetic system for producing fiux in said armature, a holder for a replaceable stylus formed in said armature and a permanent stylus securedthereto, said permanent stylus being in the form of an arm extending downwardly and rearwardly therefrom and a stylus point mounted upon said arm at a point lower than any other point of said pick-up but above the point of a needle inserted in said replaceable stylus holder in playing position. v

'7. In an electrical pick-up in combination a vibratile armature, a coil associated with said armature, a magnetic system for producing flux through said armature, said armature being mounted in playing position with its axisat an angle to the horizontal, means for securing a needle in said armature at an angle less than with the plane of vibration of said armature, a permanent stylus secured to said armature and laterally and vertically offset therefrom, said stylus being secured to said armature at such an angle that said stylus is substantially'normal to the record in playing position.

8. In an electrical pick-up, in combination a vibratile armature, a coil associated therewith,

a magnetic system for supplying flux to said armature, a pair of stylus carriers associated with said armature, a cover for enclosing said pick-up, said cover having an opening through which said stylus carriers extend and means for preventing foreign matter from penetrating into said pick-up, said means comprising a thin sheet of flexible material having an opening tightly surrounding said stylus holders, said sheet being mounted in intimate contact with the inside of said cover.

9. In an electric pick-up, a vibratory armature and means for mounting said armature for pivotal movement including a rigid non-magnetic member, said member having an opening through which the armature extends and a slot extending from an edge thereof to such opening.

10. In an electric pick-up, a vibratory armature and means for mounting said armature for pivotal movement including lateral extensions on the armature and a rigid non-magnetic memher having an opening through which the armature extends and a slot extending from an edge thereof to such opening, said extensions cooperating with said member.

11. In an electric pick-up, a vertically extending vibratile element having lateral extensions and means for supporting said element for pivotal movement including a rigid non-magnetic member having grooved bearing portions cooperating with said extensions and clamping members having adjacent bearing surfaces cooperating With said extensions.

12. In an electric pick-up, a vertically extending vibratile element having lateral extensions and means for supporting said element for pivotal movement including a rigid non-magnetic member having part-cylindrical grooved bearing pertions cooperating with said extensions and adjustable clamping members having adjacent partan aperture in said cover, and a washer of flexible material distinct from said damping means secured to said cover around the margin of said aperture and having a portion closely engaging the needle holder.

14. In an electric pick-up, in combination, a solid body member, an armature provided with a stylus holder, mounting means for said armature, means, comprising a cover, adapted to engage said body member with a dust tight fit and to enclose said armature and damping means with said stylus holder projecting through an aperture in said cover, and a flexible element, distinct from said damping means, in engagement with said cover adjacent to said aperture, said flexible element being provided with an opening through which said stylus holder extends in close engagement with said element.

THEODORE M. EDISON. 

